When Bulma looked through the time machine, she came across a journal. It was filled with all kinds of notes and diagrams that were clearly made by her future self, and with it she should be able to get the time machine running! She should also be able to make some fuel for it, which was a good thing since it was empty.
Outside, up in the air above Capsule Corp, Trunks and Ranch were facing their future kids, Gohan and Bulla. Despite trying to project outward confidence, Ranch and Trunks were extremely unsure about what they were doing. Below them Goten sat at a table with Mai, Pilaf, and Shu as they observed the block of instruction. Beerus, meanwhile, was sitting at a table off to the side enjoying the plate of snacks put in front of him.
"Alright," started Ranch, "since we're sort of your parents, we think it's our job to teach you a few things."
"That's right," Trunks said. "There might be things that we can show you that they don't know. So let's get right into it." Trunks powered up and turned into a Super Saiyan.
Ranch immediately followed suit, and their combined auras glowed brightly. "So," she said, "power up and show us what you got!"
Gohan and Bulla looked at each other. "But neither of us can turn into Super Saiyans yet!" he said.
Bulla nodded. "And I only just started training."
Not expecting that, the two looked at each other, unsure of what to do next.
Trunks scratched his head. "Um…oh hey!" he cried excitedly. "Fusion! You don't have to be a Super Saiyan to learn that!"
"Hmm…" Ranch looked at their future kids uncertainly. "Er—uh, Gohan, how much stronger than Bulla are you?"
"By a bunch," Gohan replied in a manner that annoyed his sister. "I've been training for years now."
"Then fusion might not work," Ranch said to Trunks. "You've got to be of a similar size and strength, remember? And he's a lot taller, too. Maybe when they're both older, but right now I doubt they'll be able to do it."
"I guess," Trunks said, slightly dejected. He then asked Gohan, "How old are you, anyway?"
"Nine."
"What?" he exclaimed in shock. "But you're almost as tall as me already! How is that fair?"
Ranch chuckled. "Obviously he gets that from my side."
Trunks sighed as they both powered back down. "Whatever. So you two want ice cream or something?"
"Yeah!" Gohan and Bulla said excitedly.
"Now, honey, we shouldn't spoil their dinner," Ranch jested.
"What're you talking about? They just ate," Trunks said dimly, as they all descended.
When they touched down, Bulla suddenly ran up to Beerus, and brightly asked, "Kitty, want to play?"
Beerus gave the girl a side eyed look, as Trunks quickly ran up and grabbed her by the head, pushing her down so that she both bowed with him. "I'm sorry about my daughter, Lord Beerus! Please forgive this." Thankfully Beerus just waved them away, and Trunks got Bulla out of there.
Mai commented, "Wow, Trunks and Ranch fell into suddenly being parents really well."
"They sure did," Goten agreed uneasily, not liking how impressed she was. Deciding to take action, he stood up and said, "I should show them stuff, too." But before he got anywhere, though, Chi-Chi appeared with Gohan , Goku, Krillin, and Piccolo.
"Hey, everyone, sorry we took so long," Goku said. "I had to wait for Gohan to get out of his meeting."
"Dad, if you had just told the secretary it was a family emergency I could have just left," Gohan said, annoyed at his father.
Chi-Chi then stormed up and bounded down upon her younger son. "Goten, what the heck were you thinking leaving school?" she demanded angrily. "You promised me you wouldn't do this exact thing when I finally let you attend school like Ranch!"
Nervously, he said, "But mom! There was serious stuff going on here!" Goten immediately pointed at the kids. "They're Ranch's future kids, so I'm their uncle—I think," he added unsurely. "I should be here, too!"
"We have an uncle?" Bulla asked, confused.
Her brother shrugged. "Not that I know of."
Panicked, Goten said, "Wait? You mean you don't know me in the future?"
His brother put a hand on his shoulder, and gently explained, "Sorry, Goten, but you never existed in their timeline." While Goten was stunned and tried to process that information, Gohan went up to the kids. "Hi, I'm Gohan."
"No, this is Gohan," Bulla said, pointing at her brother.
"He's mom's cousin, dummy," her brother said obviously. "You know, the one who trained her and dad when they were kids?" He turned to his namesake's counterpart, and said, "I'm Gohan, too, and this is my sister Bulla."
"Despite the circumstances it's good to meet you two," Gohan greeted, sticking his hand out. "Your parents were a great help when they came to help us here all those years ago. Whatever happened I'm sure they're okay."
Gohan took Gohan's hand and shook it. "Thanks."
Chi-Chi then forgot all about her anger with Goten, and got in front of the future kids. "My goodness! Poor babies, Goku didn't say too much but you two must be so scared!"
"We're fine, Aunt Chi-Chi, our grandpas are going to help out," young Gohan said confidently.
Chi-Chi nodded. "Good. Between them and Goku, they'll be sure to fix whatever is going on."
"Actually," Launch began, "it's just going to be Vegeta and Raditz working together on this."
The older Gohan immediately began to laugh. "Good one, Aunt Launch!" When he saw that she didn't join in on the laughter, he stopped and stared. "Wait, you can't be serious."
"I am," she informed him. "They're even training together in the gravity room right now."
Gohan then gave Goku an amused look. "Wow, dad, I never thought I'd see the day that Uncle Raditz and Vegeta would bench you to work together."
"Don't rub it in," he complained.
In the future Goku Black was surveying the ruins of the city in search of his prey. They had given him the slip after they fought to protect whatever that object that floated in the sky was before it disappeared. He went back to where he last saw them and began restart his search for their ki. All of a sudden, though, the time ring on his finger began to react to something.
"Hi there," Krillin greeted, walking up to the kids from the future. "I'm Krillin. Piccolo and I fought with your folks back in the day."
"They're fine warriors," Piccolo said affirmatively. "I was proud to fight alongside them."
"Um, thanks," Gohan said, looking at them uncertainly.
Piccolo went over to Goku, asking, "So, what's the situation, Goku?"
"Well, you see…"
All of a sudden a thunderstorm appeared, and a portal opened up in the sky. Through it emerged a figure that looked like Goku but in black clothing appear before them. As they all stared up at him in astonishment, Gohan immediately got in front of Bulla to shield her. Goku Black surveyed the scene before him, taking a close look at each face, recognizing Beerus. His eyes roved over two children, the only ones there that truly looked at him with fear. Now it made sense, they must be the children of his prey, and they traveled to the past. If he took them hostage he should be able to find their parents easily. Meanwhile, Whis pointed out to Beerus the ring that the stranger was wearing.
"Whoa, that looks like dad. What's happening?" Gohan asked, staring up at him.
Goku grinned and cracked his knuckles. "Raditz and Vegeta aren't here to stop me." Looking over at the kids from the future, he said to them, "Don't you worry; Uncle Goku will take care of things here." Making gleeful sounds, he flew up at Black and met him midair.
"Well, Goku," said Black. "You're looking well."
"Man, this is weird," commented Goku. "It's like looking into a mirror. I don't know who or what you are, but that doesn't matter." He got into a fighting stance. "How about you show me how strong you are before my brother and Vegeta get back?"
"It would be an honor," he replied. "I always wondered what it'd be like to fight you in this body."
"What's that supposed to mean?"
"You don't need to know the answer to that." Black produced a large energy ball and launched it at Goku, who blocked it but pushed him far back, all the way out of the city and to a rocky area. Goku Black flew off after him. Piccolo, Krillin, and Gohan all took to the air in their direction to watch the fight. "Stay here," young Gohan said to Bulla, also taking off. Bulla looked scared for a second, but then she shook her head, put on a brave face, and followed. Before anyone could stop them, Goten, Trunks, and Ranch all followed too. All the adults yelled for the kids to come back, but they were ignored.
"What the hell is going on? What's that energy we just felt?" Vegeta asked, running up to them with Raditz.
"That bad guy from the future showed up," Bulma told him. "He and Goku are going to fight."
"Damn it, Kakarot!" Raditz growled, as he and Vegeta powered up as they flew off to follow.
"Goku versus Goku," Beerus said with a grin. "This ought to be interesting."
Black found Goku at the rocky area, and Goku only smiled as he guessed that Black must be even more powerful than what he just displayed. Goku immediately went to Super Saiyan 2. The two began to exchange blows, as back at Capsule Corp Whis was broadcasting the fight for everyone who had stayed behind to watch.
When they caught up to everyone, Raditz shouted to Goku, "Kakarot, didn't we tell you to stay out of this?"
"Sorry, I've got dibs!" Goku said, continuing his fight with Black.
When Black threw a punch, Goku nimbly avoided it and caught his arm between his legs, and used the momentum to throw him downwards. When Goku sent a barrage of ki blasts down at him, Black recovered and landed on the ground as he took Goku's attack. Only smoke could be seen coming from the crater left behind, until it got blown away to reveal Black was unharmed.
Black then began to chuckle. "So this is the power of Goku the Super Saiyan."
"So you're like me, and like to fight strong opponents, huh?" said Goku.
"Yes." Black then powered up and unleashed a powerful black aura that swirled around him. Back at Capsule Corp the portal that brought Black over began to convulse. Black flew back up, saying, "The power of the warrior race's ultimate warrior. Let's keep this going." He charged at Goku, throwing punch after punch at him. Black kept up the punches, allowing Goku to only block and duck, until Black threw an uppercut that caught him in the gut.
Black then kicked Goku away, and sent several ki blasts at him that Goku had to fly around to evade. When they went back to hand-to-hand combat, Raditz grew more and more irritated. His brother's habit of not immediately going all out against an enemy always grated on him. Then Black and Goku each threw a punch, and made contact with each other's faces. Grinning, the two retracted their punches and floated away to put some distance between them.
"What're you waiting for?" asked Goku.
"Same to you," replied Black.
"I'm waiting for you to be at full power."
"What's the rush? Let's just keep at this."
"What the heck?" the young Gohan blabbered. "Why are they talking so much?"
"This is pretty normal," Goten informed him.
"Well how come no one's helping him?" he asked, indicating his grandfathers in particular.
"That's normal, too."
"So I have to work you up to get you to full power?" said Goku. He charged his power up, and rushed in at Black once more. Goku managed to get several good hits in on Black, until Black caught Goku's wrist and hurled Goku down into a rock formation.
As Black looked down at Goku, the portal began to pulsate more, causing him to get distracted as a strange feeling hit him. That was enough to allow Goku to lunge back up and deliver a kick that sent Black all the way back to Capsule Corp.
Stopping in midair, Black looked to be in injured before he smiled manically and said, "Amazing. This pain will only make me stronger."
Confused, Goku said, "You're pretty creepy."
Black just powered up to once again increasing his power. He charged up a large ball of energy that shot a Goku, who deflected it with his arms. But that was just a distraction as Black charged in and kicked Goku to the ground, creating a gust that knocked over the time machine.
"Oh no, the time machine!" yelped young Gohan.
Those words caught Black's attention. "Time machine? Of course."
"Don't look away!" shouted Goku as he quickly flew in to deliver a hard punch to the gut.
Black backed off and powered back up. He and Goku threw a single punch that connected, causing the two of them to start trying to overpower each other. Suddenly Black's time ring began to react again, and he found himself starting to get sucked back into the portal.
Powering down, Goku asked, "What's going on?"
Black realized that the temporal distortion caused by the time machine was correcting itself and pulling Black back to the future. Angry at not being able to take the children hostage, Black aimed a ki blast at the time machine, causing it to explode. He may still have to contend with the Saiyans back in the future, but at least now no one else can follow him and interfere.
"No, the time machine!" the young Gohan repeated in dismay.
"No!" cried Bull, as she and her brother flew down to the flaming wreckage. Black was the completely sucked through, and he disappeared.
Gohan fell to his knees and slammed his fists on the ground. "Damn!" he shouted, as hopelessness overtook him. "Why?"
Tears fell from Bulla's eyes, and she began to cry as the others began to gather around them. "Mommy! Daddy! We can't help now!"
"Hey," Ranch started off uncertainly, putting a hand on their shoulders. "I don't know how, but we'll figure something out."
As Goten assisted the Pilaf Gang in putting the fire out, Trunk thought for a second and asked his mother, "Mom, can't you fix it?"
"Not from scratch, no," she bemoaned.
"Not even with that notebook?"
She looked through the notebook, before solemnly replying, "No, I don't think so." Watching her grandchildren wallow in dismay, Bulma continued to think. Then, it finally hit her. "That's it!" She ran back to her lab.
Later, as Beerus and Whis passively discussed Supreme Kais and Time Rings with the adults, the kids from the future were still by the wreckage of the time machine, lamenting at the thought of never being able to return home and see their family again. Trunks and Ranch did their best to console their future children, but it helped very little, if at all.
That was when Vegeta and Raditz approached. "Don't give up hope," Vegeta told them. "There's always a way."
Raditz nodded, saying, "Even during the darkest times we've managed to pull through somehow. I assure you that this will be no different."
Hearing this, Beerus scoffed. "Now, I wonder what they're going to do?" He eyed the kids, adding, "If they really want their family back so bad, they should just accept what happened and get used to the fact their parents are now far younger."
But right then Bulma showed back up looking ragged but excited. She pushed the button on a capsule, tossed it, and out popped another time machine, although it was very dilapidated. Bulma proceeded to explain to everyone how it was the one Cell had taken to arrive in their timeline, and how back in the day she had asked Trunks if she could have it. Vegeta and Raditz were ready to go immediately, but Bulma shot them down, saying how she had to repair it first. When she finished her explanation, Gohan and Bulla ran up and hugged their grandmother.